In general, a strut-type suspension is mainly used for a front wheel of a four-wheeled motor vehicle, and is so arranged that a strut assembly incorporating a hydraulic shock absorber in an outer cylinder integrated with a main shaft is combined with a suspension coil spring. Among such suspensions, there is a type in which when the strut assembly rotates together with the coil spring in the steering operation, the piston rod of the strut assembly rotates, and a type in which the piston rod does not rotate. In either type, there are cases where, instead of a rolling ball bearing, a synthetic resin-made sliding bearing is used between a mounting member on the vehicle body and an upper spring seat of the coil spring, so as to allow smooth rotation of the strut assembly.